[0001] The present invention relates to the healing of wounds and, more particularly, to
a disposable wound fluids canister apparatus for closing wounds.
[0002] Wound closure involves epithelial and subcutaneous tissue adjacent the wound migrating
towards the centre of the wound until it closes. Unfortunately, closure is difficult
with large wounds or wounds that have become infected. In such wounds, a zone of stasis
(i.e. an area in which localized swelling of tissue restricts the flow of blood to
the tissues) forms near the surface of the wound. Without sufficient blood flow, the
epithelial and subcutaneous tissues surrounding the wound not only receive diminished
oxygen and nutrients, but are also less able to successfully fight bacterial infection
and, thus are less able to close the wound naturally. Such wounds have presented difficulties
to medical personnel for many years.
[0003] The most common technique for closing open wounds has been the use of sutures or
staples. Although such mechanical closure techniques are widely practised and often
effective, they suffer a major disadvantage by providing tension on the skin tissue
adjacent the wound. That is, the tensile force required to achieve closure using sutures
or staples causes very high localized stresses at the suture or staple insertion point.
Such stresses commonly result in the rupture of the tissue at those points, which
can eventually cause dehiscence in wounds, providing additional tissue loss.
[0004] Moreover, some wounds harden and inflame to such a degree due to infection that closure
by stapling or suturing is not feasible. Wounds not reparable by suturing or stapling
generally require prolonged hospitalisation, with its attendant high cost, and major
surgical procedures, such as grafts of surrounding tissues. Examples of wounds not
readily treatable with staples or suturing include large, deep, open wounds, decubitus
ulcers, ulcers resulting from chronic osteomyelitis, and partial thickness burns that
subsequently develop into full thickness burns.
[0005] The above problem is discussed in WO 93/09727 which proposes as a solution a procedure
for draining the wound by applying a continuous negative pressure to the wound over
an area sufficient to promote migration of epithelial and subcutaneous tissue toward
the wound. Although WO 93/09727 deals in some detail with the clinical considerations
of this kind of treatment, the apparatus described has certain practical shortcomings.
[0006] One problem with the apparatus described in the above prior document is that no means
are disclosed for avoiding spread of infection from one patient to another or re-infection
of the patient being treated.
US-A-3 520 300 discloses a device for suctioning blood from a surgical site. EP-A-358
302 shows a bacterial filter to contain potentially infective material within a collection
container for us in a blood sampling system.
[0007] WO 96/05873 discloses a therapeutic apparatus for stimulating healing of wounds,
said apparatus including a housing that contains a vacuum pump and a chamber for holding
a disposable wound drainage collection canister. The canister preferably resides within
the chamber and connects at an outlet with the vacuum pump and at an inlet with a
porous pad. The pad is placed over a wound and adhesively secured thereto to create
a sealed environment at the wound. Thus, when the vacuum pump activates, it evacuates
air from the canister and thence the wound environment, resulting in the application
of negative pressure to the wound, which in turn tends to promote drainage of fluids
flowing from the wound into the canister. After the canister is filled, it is removed
from the chamber, disposed of, and replaced with another canister to continue therapy.
[0008] Although the vacuum pump is designed to be reusable because of its more costly components,
the apparatus utilizes a removable and disposable canister adapted to prevent contamination
of the vacuum pump or the remainder of the apparatus. If the vacuum pump or other
parts of the housing or the tubing leading to the pump from the canister became contaminated,
the wound closure apparatus would have to be completely disassembled, thoroughly cleaned
and possibly discarded. Disassembly and cleaning of the wound closure apparatus is
extremely time and labour intensive, while disposal of the wound closure apparatus
is expensive. Consequently, a removable and disposable canister prevents either of
the above undesirable circumstances from occurring.
[0009] The present invention is divided out of the disclosure of WO96/05873.
[0010] It is an object of the present invention to provide a removable and disposable wound
fluids collection canister to protect the wound closure apparatus from contamination.
This object is met by the features of claim 1.
[0011] The present invention provides a canister for use in wound treatment apparatus comprising
a wound dressing pad and a suction pump for applying negative pressure to the wound
dressing pad, said canister comprising a moulded plastics container having an inlet
for connection to a wound dressing pad and an outlet for connection to a suction pump,
said outlet incorporating a bacterial filter. Other objects, features and advantages
of the present invention will become evident to those skilled in the art in light
of the following.
[0012] Figure 1 is a perspective view depicting the vacuum pump unit of a wound closure
apparatus constructed according to the teachings of the present invention.
[0013] Figure 2 is a right side plan view depicting the vacuum pump unit of Figure 1.
[0014] Figure 2A is a detail view of the latch 26 portion of Figure 2, partially cut-away
to eliminate guide (or "key") 29 from the view and to show portions of latch 26 in
sagital cross section.
[0015] Figure 3 is a perspective view depicting a wound drainage collection canister for
use in conjunction with the vacuum pump unit of Figure 1.
[0016] Figure 4 is a rear plan view depicting the wound drainage collection canister of
Figure 3.
[0017] Figure 5 is a perspective view depicting the connection of a wound drainage collection
canister of Figure 3 to a wound pad.
[0018] Figure 6 is a front plan view in partial cross section depicting the connection of
the wound drainage collection canister of Figure 3 within the housing of the vacuum
pump of Figure 1.
[0019] Figure 6A is a partial view of the apparatus shown in Figure 6 except the canister
is removed.
[0020] Figure 7 is a perspective view depicting the filter carrier of the wound drainage
collection canister.
[0021] Figure 8 is a top plan view depicting the filter cap of the wound drainage collection
canister.
[0022] Figure 9 is a schematic view depicting the control system for a wound closure apparatus
constructed according to the teachings of the present invention, and
[0023] Figure 10 is a section through a wound showing the wound pad in place.
[0024] As illustrated in Figures 1 and 2, front housing 11 and rear housing 12 connect together
using any suitable means such as screws and fasteners to provide wound closure vacuum
pump 10 with a small, compact, and easily portable carrying case. Consequently, front
housing 11 and rear housing 12 connect together to form handle 13 that permits easy
carrying of wound closure apparatus 10. Except as maybe otherwise evident from this
description, the carrying case of vacuum pump 10 is substantially as described and
shown in WIPO Design No. DM/032185.
[0025] Front housing 11 includes power switch 15 that is movable between an on and off position
to permit user control of the delivery of power to wound closure apparatus 10. Keypad
16 and liquid crystal display (LCD) 17 mount to front housing 11 to permit the programming
of wound closure apparatus 10. Chamber 18 is defined by integrally formed interior
side walls 100 and 101, top wall 102, bottom wall 103 and rear wall 104. Side wall
100 is dependently attached to the interior of front housing 11 by standard mounting
hardware (not shown). The would fluids collection canister, illustrated in Figures
3-5, is received within chamber 18. Side walls 100 and 101 each include a key 29 and
30, respectively, the aid in the alignment of wound fluids collection canister 19
within chamber 18. Furthermore, front housing 11 includes latch 26 to secure the wound
fluids collection canister within chamber 18.
[0026] Rear housing 12 includes arm 14 pivotally mounted to it within recess 110. An identical
arm pivotally mounts to the opposite side of rear housing 12 within an identical recess.
Arm 14 and its corresponding arm mounted on the opposite side of rear housing 12 pivot
from within their recesses to a position where they support wound closure apparatus
10 at an angle. Arm 14 and its corresponding arm angularly support wound closure apparatus
10 to permit easier user access to keypad 16. Arm 14 and its corresponding arm may
also be used to permit hanging of apparatus 10 from a hospital bed foot board.
[0027] Canister 19 has a shape as shown in Figures 3 to 6. As illustrated in Figures 3 to
6, canister 19 includes sidewalls 20 and 21, top wall 23, bottom wall 24, back wall
22 and front wall 25 that define the rectangular chamber for receiving blood, pus,
and other fluids emitted from a wound. Sidewalls 20 and 21 include keyways 27 and
31 respectively, that receive a respective one of keys 29 and 30 to provide easy alignment
of canister 19 within chamber 18. Furthermore, keyway 27 includes recess 28 that receives
latch 26 to fasten canister 19 within chamber 18.
[0028] Front wall 25 of canister 19 includes raised portion 32 extending therefrom to furnish
a window that permits a user to determine the level of wound fluids within canister
19. Accordingly, raised portion 32 is transparent so that the level of wound fluids
within canister 19 may be visually determined. Raised portion 32 includes sidewalls
110 and 111, top wall 112, bottom wall 113, and front face 114 that define a chamber
which opens into the chamber defined by sidewalls 20 and 21, top wall 23, bottom wall
24, back wall 22 and front wall 25 of canister 19. Front face 114 of raised portion
32 includes graduations that demarcate the volume of wound fluid within canister 19.
Additionally, sidewalls 110 and 111 of raised portion 32 include ridges that provide
a gripping surface for the user during the insertion and removal of canister 19 from
chamber 18.
[0029] Although raised portion 32 is transparent to permit the determination of the level
of wound fluids within canister 19, sidewalls 20 and 21, back wall 22, top wall 23,
bottom wall 24, and front wall 25 are opaque or textured so that they are only translucent.
As an alternative, the portions of canister 19 surrounding filter 46 may also be transparent.
This enables a user to visually check for signs of contamination of filter 46. In
this preferred embodiment, sidewalls 20 and 21, back wall 22, top wall 23, bottom
wall 24, front wall 25, and raised portion 32 of canister 19 are fabricated from a
plastics material.
[0030] Canister 19 includes inlet 35 that is formed integrally with top wall 112 of raised
portion 32. Inlet 35 is cylindrical in shape and communicates with the interior of
canister 19 to permit the transfer of wound fluids into canister 19. In this preferred
embodiment, inlet 35 is also fabricated from a plastics material.
[0031] In order to prevent liquids sucked into the canister from splashing directly onto
cap 49, which masks the outlet 44, and to reduce foaming within the canister, inlet
35 has a blind inner end. Inlet 35 has a slot 35A so that drainage fluid is deflected
downwardly into the raised handle portion 32 of the canister. Handle portion 32 may
communicate with the main part of the canister through one or more holes in wall 25.
It is desirable to avoid foaming because this can give a false reading when a capacitance
sensing device is used to sense when the canister is filled. An anti-foaming material,
e.g. a silicone may be added to the canister, e.g. by coating the interior walls.
It may also be advantageous to include a gel-forming substance, e.g. a polyacrylamide
or modified starch in order to immobilise the drainage fluid. This is particularly
useful if the apparatus is likely to be tilted.
[0032] Wound fluids (i.e. drainage) are communicated through inlet 35 into canister 19 via
pad 36 and hoses 37 and 38. In this preferred embodiment, pad 36 is fabricated from
an open cell polyurethane or polyether foam. Hose 37 is inserted within pad 36 by
making an incision in pad 36 and inserting the end of hose 37. Hose 37 can then be
secured within pad 36 using any suitable means such as an adhesive or a flange. Preferably,
the foam pad is moulded or formed with an elongated hole for the drainage tube which
is an interference fit with the tube. The hoses are preferably made from medical grade
PVC tube. Hose 38 mounts within inlet 35 using any suitable means such as an adhesive
or welding. Hoses 37 and 38 include luer lock connectors 39 and 40, respectively,
(or the equivalent such as any known quick disconnect type coupling) that attach together
to permit communication between hoses 37 and 38. Furthermore, hoses 37 and 38 include
pinch clamps 41 and 42, respectively, that are capable of sealing their respective
hose 37 or 38 to prevent the flow of wound fluids. The foam pad is preferably packaged
in a sterile container together with its connector and clamp. When packaged, the clamps
will be in their open condition.
[0033] The communication of wound fluids into canister 19 requires the securing of pad 36
over a wound. Pad 36 is secured over a wound using cover 43 which is fabricated from
a plastics material and includes an adhesive on one side that sticks to human skin.
Wound cover 43 is conveniently a surgical drape material comprising a sheet of elastomeric
material coated peripherally or overall with a pressure-sensitive adhesive, such as
an acrylic adhesive. The elastomeric or rubbery nature of the wound cover is important
because it accommodates changes in pressure in the wound area during intermittent
operation of the vacuum pump. The wound cover is preferably a polyurethane film with
a removable backing sheet, i.e. of polythene to protect the adhesive surface.
[0034] A high degree of reticulation in the polymer foam is desirable to achieve good permeability
when the foam is under suction. Foams having at least 90% and especially at least
95% of interconnecting cells are preferred.
[0035] In use, the foam pad is cut to a size which corresponds closely to the edge of the
wound with the objective of packing the foam into the wound cavity 210 so that it
contacts the surface of the cavity, rather than bridging the cavity. As depicted in
Figure 10, the cavity may be extensive and there may be little or no tissue coverage
to the bone 212. This is illustrated diagrammatically in Figure 10. Figure 10 is a
cross-section through a wound showing the foam pad 36 packed into the wound cavity
210. It is important that the foam should be firmly packed into the recesses of the
wound cavity. Drainage tube 37 terminates within the centre of the foam pad 36. Surgical
drape 43 extends over the foam pad and is adhered to intact skin 211 around the periphery
of the wound. Drape 43 is also firmly adhered around the tube 37 to prevent leakage
of air. A wound cover is then adhered to the surrounding skin and around the drainage
tube to provide an air-tight seal around the wound.
[0036] As illustrated in Figures 2, 4 and 6, canister 19 includes outlet 44 that mounts
over port 45 to permit wound closure apparatus 10 to draw wound fluids into canister
19. Outlet 44 is cylindrically shaped and formed as an integral part of back wall
22 by outer wall 33 and inner wall 50 which are interconnected by end wall 34. Passageway
52, defined in part by interior wall 50 and in part by filter cap 49, provides the
actual conduit for outlet 44 between the interior and exterior of canister 19. The
placement of canister 19 within recess 18 such that outlet 44 resides over port 45
couples canister 19 to a vacuum pump. The vacuum pump removes air from canister 19
to create vacuum pressure within canister 19. That vacuum pressure is then transmitted
to a wound site through hoses 37 and 38, thereby not only enabling therapeutic use
of system 10, but also tending to promote wound drainage. Any wound drainage fluid
is then drawn through pad 36 and hoses 37 and 38 into canister 19.
[0037] Outlet 44 resides near top wall 23 of canister 19 to ensure efficient operation of
the vacuum pump. That is, the vacuum pump removes the most air from canister 19 when
the air does not have to first bubble through wound fluids contained in canister 19.
Consequently, with outlet 44 positioned near the top of canister 19, the vacuum pump
removes air directly from canister 19, and it is only during the final filling of
canister 19 that air must bubble through wound fluids. Preferably, as described below,
the apparatus includes detecting and warning means which operates before the level
of the drainage fluid reaches either the inlet or outlet tube so that a fresh canister
can be installed.
[0038] In removing fluids from a wound utilizing wound closure apparatus 10, a major safety
concern is preventing wound fluids from contaminating the vacuum pump. Accordingly,
filter 46 mounts over outlet 44 utilizing filter carrier 48 and filter cap 49 to block
the flow of wound fluids to outlet 44 so that wound fluids remain within canister
19 and do not flow into the vacuum pump. In this preferred embodiment, filter 46 is
a 0.2 micron hydrophobic membrane filter providing a bacterial barrier, although other
filters may be substituted as appropriate.
[0039] As illustrated in Figure 7, filter carrier 48 includes face 53 formed integrally
with lip 54. Face 53 includes groove 56 formed therein, while lip 54 supports brace
55 in its interior. Filter 46 fits within groove 56 of face 54 and is supported within
filter carrier 48 by brace 55 of lip 54. An 'O' ring 53A is fitted in peripheral recess
of filter carrier 48 to accommodate manufacturing tolerances and ensure a fluid tight
seal in filter cap 49.
[0040] As illustrated in Figures 6 and 8, filter cap 49 includes cylindrical portions 57
and 58 which are formed integrally (with annulus 57' spanning therebetween), to hold
filter carrier 48 within passageway 52 of outlet 44. To mount filter 46 over passageway
52, filter 46 is first placed within filter carrier 48 as described above. Filter
carrier 48 is then positioned within filter cap 49 such that face 53 abuts annulus
57' of filter cap 49 and lip 54 of filter carrier 48 resides within annular lip 50'
of outlet 44. Accordingly, when cylindrical portion 57 of filter cap 49 mounts over
outlet 44, the front face 53 of filter carrier 48 and the outer edges of filter 46
abut annulus 57' to secure filter 46 within passageway 52. Filter cap 49 attaches
to outlet 44 using any suitable means such as an adhesive or welding. Filter cap 49
is completely sealed except for aperture 51 positioned on top of filter cap 49. Aperture
51 communicates with port 45 via passageway 52 of outlet 44 to permit the vacuum pump
to draw air from the interior of canister 19.
[0041] As illustrated in Figures 2 and 6, port 45 includes O-ring 59 mounted thereabout
to provide a fluid tight seal between port 45 and inner wall 50 of outlet 44. Port
45 mounts through rear wall 104 of chamber 18 using any suitable means such as nuts
60 and 61. Furthermore, hose 62 attaches to the rear of port 45 using any suitable
means such as a clamp to couple port 45 to the vacuum pump.
[0042] Switch 63 protrudes through rear wall 104 of chamber 18 to produce a signal indicating
when canister 19 properly and securely resides within chamber 18. In this preferred
embodiment, switch 63 is a normally open push button switch that mounts on rear wall
104 of chamber 18 using any suitable means such as a bracket. When canister 19 is
properly positioned within chamber 18, its rear wall 22 presses the head of switch
63, closing switch 63 so that it provides a signal indicating that canister 19 properly
resides within chamber 18.
[0043] Fill sensor 64 resides adjacent side wall 101, exterior to chamber 18. Fill sensor
64 provides a signal that indicates when canister 19 is filled with wound debris.
In this preferred embodiment, fill sensor 64 is a capacitive sensor that mounts on
side wall 101 of chamber 18 using any suitable means such as a bracket or appropriate
adhesive material. Fill sensor 64 has a sensing profile 64A which determines the point
at which the capacitance measurement is made. When wound fluids have reached the level
within canister 19 which corresponds to the location of the sensing profile 64A, the
capacitance within canister 19 as 'seen' by fill sensor 64 changes, resulting in fill
sensor 64 outputting a signal indicating that canister 19 is filled with wound fluids
to the level at which the sensing profile is located. The position of this sensing
profile behind wall 101 can be changed (see Figure 6A) to provide an optimum balance
of space and volume utility.
[0044] As illustrated in Figure 2A, latch 26 generally comprises latch pin 65, handle 66
latch guide sleeve 68A and spring 67. Latch pin 65 comprises a proximal end 65A and
distal end 65B. Latch guide sleeve 68A abuts the inner surface of front housing 11
and is held securely in place from the outer side of front housing 11 by nut 68B.
Handle 66 screws onto the proximal end 65A of latch pin 65 and is locked in position
by nut 69A. In the preferred embodiment, cover 68 over nuts 69A and 68B provides a
surface against which handle 66 abuts, thus preventing end 65B from excessively entering
chamber 18 as will be understood further herein. Cover 68 also provides aesthetic
enclosure of nuts 69A and 68B. Dependent attachment of side wall 100 (chamber 18),
as described hereinabove, is such that side wall 100 abuts latch guide sleeve 68A
on the side distal front housing 11. Further, this arrangement causes distal end 65B
of latch pin 65 to project into chamber 18 under the force of spring 67 (shown partially
cut away). Spring 67 resides circumferentially about latch pin 65 within an axial
bore of latch pin guide 68A. Spring 67 exerts force between distal end 65B of latch
pin 65 and an annulus within the axial bore of latch pin guide 68A. A transverse slot
in the distal end of latch pin guide 68A receives end 65B of latch pin 65, providing
rotational alignment of end 65B and further recess for end 65B when a user "pulls"
handle 66 in an axial direction.
[0045] Latch 26 operates to ensure canister 19 remains secured within chamber 18. End 65B
of latch 26 terminates in a point that protrudes through key 29 into chamber 18. During
the placing of canister 19 within chamber 18, key way 27 of canister 19 forces the
point 65B of the latch pin within key 29. However, once canister 19 has been properly
positioned within chamber 18, recess 28 resides below latch pin end 65B so that spring
67 biases the point 65B of latch pin 65 into recess 28 to prevent the removal of canister
19 from chamber 18. The removal of canister 19 from chamber 18 is accomplished by
grasping handle 66 and pulling the point 65B of latch pin 65 from recess 28. With
the point of latch pin 65 no longer within recess 28, canister 19 may be pulled from
chamber 18 using its raised portion 32.
[0046] As illustrated in Figure 9, wound closure apparatus 10 preferably plugs into a standard
115/120 VAC power source (e.g. an outlet) to supply power to control system 70. Alternative
embodiments (not shown, although similar) are readily adapted for 220 VAC power by
changing the power cord and appropriately re-wiring the tops of the transformer within
the DC power supply 71 as is readily know in the art. The application of power to
control system 70 is regulated by power switch 15 which is a standard push button
on/off switch. With power switch 15 depressed, DC power supply 71 receives the 115/120
VAC signal and converts it into a 12 VDC signal for use by fan 74 and motor 83. A
conventional voltage regulator 96 steps down the voltage to +5V or 12V for use by
each of the other DC components 63, 16, 17, 82, 72 and 75. Voltage regulator 96 connects
to keypad 16, LCD 17, switch 63, microcontroller 72, transducer 75, and tilt sensor
82 to supply each of them with the +5V DC signal. Microcontroller 72 links to solid
state relays (MOSFETs) 97 and 98 for controlling the provision of the 12 VDC power
supply to fan 74, pump motor 83 and fill sensor 64, respectively.
[0047] As illustrated in Figure 1, once power switch 15 is depressed, a user employs keypad
16 and LCD 17 to select the operating parameters for wound closure apparatus 10. Wound
closure apparatus 10 stores the previously selected operating parameters so that upon
power initialization, LCD 17 displays the phrase "NEW PATIENT" with the word "NO"
over arrow button 76, and the word "YES" over arrow button 77. If the user presses
arrow button 76 to answer no, wound closure apparatus 10 will operate at the previously
selected parameters. After answering no, the user presses on/off button 78 to begin
operation of wound closure apparatus 10.
[0048] Conversely, if the user presses arrow button 77 to indicate a new patient, wound
closure apparatus 10 will operate either under default values or allow the user to
select the operating parameters. To operate under default parameters, the user presses
on/off button 78 after pressing arrow button 77. However, to select his or her own
values, the user presses option button 79 after pressing arrow button 77.
[0049] Upon the pressing of option buttons 79, LCD 17 displays a bar graph representing
the spectrum of available vacuum pump pressures and a numerical representation of
the vacuum pump pressure presently displayed by the bar graph. The user changes vacuum
pump pressure using arrow buttons 76 and 77. The pressing of arrow button 76 reduces
vacuum pump pressure, while the pressing of arrow button 77 increases vacuum pump
pressure. After selecting the desired vacuum pump pressure, the user presses option
button 79 to save the selected vacuum pump pressure.
[0050] Once the selected vacuum pump pressure has been saved, LCD 17 displays the pump operation
times available to the user. The user may program wound closure apparatus 10 to pump
either continuously or intermittently. Thus, LCD 17 displays the word "CONTINUOUS"
over arrow button 76 and "INTERMITTENT" over arrow button 77. The user selects continuous
operation by pressing arrow button 76 followed by on/off button 78 to activate the
vacuum pump. In its continuous mode, wound closure apparatus 10 runs its vacuum pump
continuously until on/off button 78 is pressed again.
[0051] If the user presses arrow button 77 to select intermittent operation, LCD 17 displays
a bar graph or figures representing the minimum and maximum on times for the vacuum
pump. LCD 17 also displays the phrase "ON TIME" and the numerical value presently
displayed. A user decreases the on time of the vacuum pump by pressing arrow button
76 and increases the on time of the vacuum pump by pressing arrow button 77. After
selecting the desired on time, the user presses options button 79 to save the selected
on time value.
[0052] LCD 17 then displays a second bar graph or figures representing the off time for
the vacuum pump with the phrase "OFF TIME" and the numerical value presently depicted
by the bar graph. Again, arrow buttons 76 and 77 are pressed to increase or decrease,
respectively, the off time for the vacuum pump. After selecting the off time, the
user presses options button 79 followed by on/off button 78 to operate wound closure
apparatus 10 using the selected parameters.
[0053] Keypad 16 includes setting button 80 to permit the user to sequentially display the
currently selected operating parameters of wound closure apparatus 10. Keypad 16 further
includes delay button 81 to permit the user to deactivate an alarm sounded in response
to an improper operating condition of wound closure apparatus 10. Delay button 81
provides the user with the ability to silence alarms so that the alarm will not have
to be listened to during the correction of the problem.
[0054] Any new alarm conditions occurring within the fifteen minute period ("delay period")
after the pressing of delay button 81 will not be indicated by an audible alarm. However,
the pump will still be deactivated when appropriate, even during the delay period.
[0055] Again referring to Figure 9, microcontroller 72 is a multi-port microprocessor with
a eight-bit analog to digital (A/D) converter having associated memory that stores
the program directing microcontroller 72 during its control of wound closure apparatus
10. After receiving and storing the user selected operational parameters and receiving
an on signal due to the pressing of on/off button 78, microcontroller 72 activates
pump motor 83 which, in turn, drives vacuum pump 84 to begin the removal of air from
canister 19.
[0056] As vacuum pump 84 operates, it draws air from within canister 19, into hose 62 via
outlet 44 of canister 19 and port 45. Hose 62 connects to filter 85 and transducer
75 via T-junction 91. Filter 85 is similar to filter 46 and thus ensures no wound
fluids contaminate vacuum pump 84. Filter 85 communicates with pump 84 via T-junction
88 and one arm of the latter is connected to bleed valve 86. Bleed valve 86 communicates
with the atmosphere to release pressure developed within line 62 by vacuum pump 84
after microcontroller 72 deactivates vacuum pump 84. Bleed valve 86 is sufficiently
small to ensure that it generally does not affect the vacuum pressure levels achieved
by vacuum pump 84 as it evacuates air from canister 19, except to prevent over pressurisation
beyond 33,3 KPa (250 mmHg) and to prevent erratic operation of the vacuum pump at
very low pressure settings..
[0057] In the preferred embodiment, an orifice of 0.5 mm diameter is especially preferred
for bleed valve 86. Valve 86 or the equivalent is particularly important for enabling
intermittent application of negative pressure, as the orifice allows for gradual release
of the negative pressure (over a period of about fifteen seconds) when the pump motor
83 is de-actuated. Bleed valve 86 is positioned outside housing 11 to facilitate un-clogging
of aperture 86 in the event of a blockage. An aperture is provided in bleed valve
86, which is machined from stainless steel. Flow control orifices would be alternatives.
[0058] Line 62 also includes T-connector 91 to connect it with line 92. Line 92 is connected
to tank 94 which acts as a damper to pressure changes in line 62. This dampening effect,
facilitated by restrictor 89 in line 93 between transducer 75 and T-junction 91, causes
the pressure measured by transducer 75 to be an accurate indication of actual wound
site pressure. Transducer 75 communicates with line 62 via line 93 to measure tank
94 pressure and produce an electrical signal representative of that pressure. Transducer
75 outputs its pressure signal to microcontroller 72.
[0059] Microcontroller 72 utilizes the pressure signal to control the speed of pump motor
83. As previously described, the user selects either a default vacuum pump pressure
or a desired vacuum pump pressure for the operation of wound closure apparatus 10.
After receiving the wound pressure signal from transducer 75, microcontroller 72 compares
the wound pressure with the user selected pressure. If the wound pressure is higher
than the user selected vacuum pump pressure, microcontroller 72 reduces pump motor
speed to decrease vacuum pump pressure and thus the pressure at the wound. Conversely,
if the wound pressure is less than the user selected vacuum pump pressure, microcontroller
72 increases the speed of pump motor 83 resulting in an increase in the vacuum pressure
applied at the wound.
[0060] Microcontroller 72 controls pump motor 83 by varying the amount of voltage received
by pump motor 83. That is, microcontroller 72 receives the 12V DC signal from DC power
supply 71 and outputs a voltage between 0 and 12V DC to pump motor 83 to control its
speed in accordance with the user selected vacuum pump pressure value. Accordingly,
microcontroller 72 employs feedback to ensure that the wound experiences the user
selected vacuum pump pressure. If the target pressure is not reached after a period
of five minutes, microcontroller 72 deactivates motor 83 and sounds the audible alarm.
Additionally, the feedback signal prevents maximum vacuum pump pressure from being
exceeded. If the wound pressure measured by transducer 75 exceeds a maximum safe vacuum
pump pressure, microcontroller 72 deactivates pump motor 83.
[0061] Wound closure apparatus 10 includes fan 74 to cool pump motor 83 and printed circuit
board or chassis 200 during the operation of the wound closure apparatus 10. In the
preferred embodiment, microcontroller 72 controls fan 74 to always operate while power
is being supplied. In alternative embodiments, however, microcontroller 72 controls
fan 74 to operate only in relation to motor 83, because it is only necessary for fan
74 to operate if motor 83 is also operating. In such alternative, as long as pump
motor 83 operates, microcontroller 72 runs fan 74. However, when microcontroller 72
deactivates pump motor 83 it also deactivates fan 74.
[0062] Control system 70 includes fill sensor 64 to provide a signal to microcontroller
72 that indicates when canister 19 is completely filled with wound fluids. After receiving
a signal from fill sensor 64, microcontroller 72 deactivates pump motor 83 and fan
74 and activates alarm 95 to signal the user that canister 19 must be replaced.
[0063] Control system 70 includes switch 63 to prevent users from operating wound closure
apparatus 10 without a canister properly installed. If a canister is not properly
installed, switch 63 remains open and therefore outputs no signal to microcontroller
72. If microcontroller 72 receives no signal from switch 63, indicating no canister
within chamber 18, it will not supply power to pump motor 83 even after a user has
pressed on/off button 78. Furthermore, microcontroller 72 activates alarm 95 to signal
the user that either a canister is not properly installed or is improperly installed
within chamber 18 when therapy is activated. Microcontroller 72 operates pump motor
83 only if switch 63 is depressed to provide a signal indicating the proper placement
of a canister within chamber 18.
[0064] Control system 70 includes tilt sensor 82 to prevent operation of wound closure apparatus
10 if it is tilted excessively. Excessive tilting of wound closure apparatus 10 during
operation diminishes the efficiency of removal of wound fluids and, more importantly,
might result in either the contamination of vacuum pump 84 or the spilling of wound
fluids. Thus, if wound closure apparatus 10 tilts along any of its axes beyond a predetermined
angle (approximately 45° in this preferred embodiment), tilt sensor 82 outputs a signal
to microcontroller 72. In response, microcontroller 72 deactivates pump motor 83 and
activates alarm 95 to signal the user of the excessive tilt situation. In this preferred
embodiment, tilt sensor 82 may be implemented with any standard mercury switch. The
tilt circuiting and alarm operates as follows. If therapy is in progress and the pump
unit is tilted, the alarm will sound and the liquid crystal display 17 will state
'unit tilted'. Therapy is automatically stopped. When the unit is returned to the
vertical, therapy will be automatically reinstated after a time delay (e.g. about
30 seconds) has elapsed..
1. A disposable canister for use in wound treatment apparatus comprising a wound dressing
pad and a suction pump for applying negative pressure to the wound dressing pad, said
canister comprising a moulded plastics container (19) having an inlet (35) connected
to a flexible inlet tube (38) and an outlet (44) for connection to the suction pump,
said outlet incorporating a bacterial filter and said inlet tube having a quick disconnect
coupling device (40) for connection to a flexible drainage tube (37) leading to the
wound dressing pad and said inlet tube (38) including clamp means (42) for preventing
escape of liquid from the container.
2. A canister as claimed in claim 1 which includes a recess (28) in a wall thereof, said
recess being engageable by a latch (26) associated with the suction pump to releasably
hold the outlet (44) in coupling engagement with a part (45) of the suction pump.
3. A canister as claimed in claim 1 or claim 2 wherein the filter (46) is retained in
the outlet (44) by means of a filter carrier (48) having a flange (53), the flange
sealing the filter between itself and an annular wall (57') of a filter cap (49).
4. A canister as claimed in any one of the preceding claims which includes deflector
means (25,35A) for deflecting liquid sucked through the inlet towards the bottom of
the canister.
5. A canister as claimed in any one of the preceding claims wherein the inlet tube (38)
is sealed into the inlet (35) adhesively or by welding.
6. A canister as claimed in any one of the preceding claims which includes an anti-foaming
substance.
7. A canister as claimed in any one of the preceding claims which includes a gel-forming
substance which is capable of immobilising drainage fluids within the canister.
8. A canister as claimed in any one of the preceding claims in combination with a wound
dressing pack, the wound dressing pack comprising a reticulated open-celled foam pad
(36) having at least 90% of interconnecting cells and being connected to a drainage
tube (37) terminating in a quick disconnect coupling device (39) adapted to couple
with coupling device (40), attached to the inlet tube (38) which is attached to the
inlet (35) of the canister, said drainage tube (37) including clamp means (41) to
prevent the drainage tube leaking liquid when the coupling devices (39,40) are disconnected.
9. The combination as claimed in claim 8 wherein said foam comprises more than about
95% interconnecting cells.
10. The combination claimed in claim 8 or 9 wherein the drainage tube (37) is fitted into
the foam pad (36) by an interference fit.
1. Einwegkanister für die Verwendung in einer Wundbehandlungsvorrichtung, umfassend ein
Wundverbandskissen und eine Saugpumpe zum Ausüben von Unterdruck auf das Wundverbandskissen,
wobei der Kanister einen geformten Kunststoffbehälter (19) mit einem Einlass (35),
der mit einem flexiblen Einlassschlauch (38) verbunden ist, und einen Auslass (44)
der Saugpumpe umfasst, wobei der Auslass einen Bakterienfilter enthält und der Einlassschlauch
eine Schnelltrennkopplungseinrichtung (40) zur Verbindung mit einem flexiblen, zum
Wundverbandskissen führenden Drainageschlauch (37) aufweist, und wobei der Einlassschlauch
(38) Klemmmittel (42) aufweist, um das Austreten von Flüssigkeit aus dem Behälter
zu verhindern.
2. Kanister nach Anspruch 1, der eine Aussparung (28) in einer Wand aufweist, wobei die
Aussparung eine Einschnappvorrichtung (26) der Saugpumpe eingreifen kann, um den Auslass
(44) lösbar in Koppeleingriff mit einem Teil (45) der Saugpumpe zu halten.
3. Kanister nach Anspruch 1 oder Anspruch 2, wobei der Filter (46) in dem Auslass (44)
mittels eines Filterträgers (48) gehalten ist, umfassend einen Flansch (53), wobei
der Flansch den Filter zwischen sich und einer ringförmigen Wand (57') einer Filterkappe
(49) dicht einschließt.
4. Kanister nach einem der vorangehenden Ansprüche, der Ableitmittel (25, 35A) zum Ableiten
von durch den Einlass gesaugter Flüssigkeit in Richtung des Bodens des Kanisters enthält.
5. Kanister nach einem der vorangehenden Ansprüche, worin der Einlassschlauch (38) an
dem Einlass (35) durch Kleben oder Schweißen dicht angebracht ist.
6. Kanister nach einem der vorangehenden Ansprüche, der eine schaumhemmende Substanz
umfasst.
7. Kanister nach einem der vorangehenden Ansprüche, der eine Gel-bildende Substanz enthält,
die Drainagefluide innerhalb des Kanisters immobilisieren kann.
8. Kanister nach einem der vorangehenden Ansprüche in Kombination mit einem Wundverbandspaket,
wobei das Wundverbandspaket ein netzartiges Offenzell-Schaum-Kissen (36) mit wenigstens
90% Verbindungszellen umfasst und mit einem Drainageschlauch (37) verbunden ist, der
in eine Schnelltrennkopplungseinrichtung (39) mündet, passend für die Verbindung mit
der Kopplungseinrichtung (40), befestigt an dem Einlassschlauch (38), der an dem Einlass
(35) des Kanisters befestigt ist, wobei der Drainageschlauch (37) Klemmmittel (41)
umfasst, um zu verhindern, dass aus dem Drainageschlauch Flüssigkeit entweicht, wenn
die Kopplungseinrichtungen (39, 40) getrennt sind.
9. Kombination nach Anspruch 8, wobei der genannte Schaum mehr als ca. 95% Verbindungzellen
enthält.
10. Kombination nach Anspruch 8 oder 9, wobei der Drainageschlauch (37) mittels eines
Preßsitzes in das Schaumkissen (36) eingepasst ist.
1. Boîte jetable destinée à être utilisée dans un appareil de traitement de plaie comprenant
une garniture de pansement et une pompe aspirante permettant d'appliquer une dépression
à la garniture de pansement, ladite boîte comprenant un conteneur moulé en matière
plastique (19) ayant une entrée (35) reliée à un tuyau d'arrivée souple (38) et une
sortie (44) pour une connexion à la pompe aspirante, ladite sortie incorporant un
filtre bactérien et ledit tuyau d'arrivée ayant un dispositif de couplage à déconnexion
rapide (40) pour une connexion à un tuyau de drainage souple (37) menant à la garniture
de pansement et ledit tuyau d'arrivée (38) comprenant des moyens de serrage (42) pour
empêcher que du liquide ne s'échappe du conteneur.
2. Boîte selon la revendication 1 qui inclut un retrait (28) situé dans une de ses parois,
ledit retrait pouvant être mis en prise par un verrou (26) associé à la pompe aspirante
afin de maintenir de manière libérable la sortie (44) dans une mise en prise de couplage
avec une partie (45) de la pompe aspirante.
3. Boîte selon l'une quelconque des revendications 1 ou 2 dans laquelle le filtre (46)
est maintenu dans la sortie (44) à l'aide d'un support de filtre (48) ayant un rebord
(53), le rebord maintenant de manière étanche le filtre entre lui-même et une paroi
annulaire (57') d'un couvercle de filtre (49).
4. Boîte selon l'une quelconque des revendications précédentes qui inclut des moyens
de déflecteur (25, 35A) permettant de défléchir le liquide aspiré à travers l'entrée
vers le fond de la boîte.
5. Boîte selon l'une quelconque des revendications précédentes dans laquelle le tuyau
d'arrivée (38) est scellé dans l'entrée (35) par collage ou par soudure.
6. Boîte selon l'une quelconque des revendications précédentes qui inclut une substance
anti-mousse.
7. Boîte selon l'une quelconque des revendications précédentes qui inclut une substance
gélifiante capable d'immobiliser les liquides de drainage dans la boîte.
8. Boîte selon l'une quelconque des revendications précédentes en combinaison avec un
ensemble de garniture de pansement, l'ensemble de garniture de pansement comprenant
une garniture de mousse réticulée à cellules ouvertes (36) ayant au moins 90 % de
cellules interconnectées, et étant reliée à un tuyau de drainage (37) se terminant
par un dispositif de couplage à déconnexion rapide (39) adapté afin de se coupler
au dispositif de couplage (40), fixé au tuyau d'arrivée (38) qui est attaché à l'entrée
(35) de la boîte, ledit tuyau de drainage (37) comprenant des moyens de serrage (41)
pour empêcher toute fuite de liquidé du tuyau de drainage quand les dispositifs de
couplage (39, 40) sont déconnectés.
9. Combinaison selon la revendication 8 dans laquelle ladite mousse comprend plus de
95 % environ de cellules interconnectées.
10. Combinaison selon l'une quelconque des revendications 8 ou 9 dans laquelle le tuyau
de drainage (37) est ajusté dans la garniture de mousse (36) par un ajustement avec
serrage.